Goodall, HJ orcid.org/0000-0002-8501-8159, Gregory, LC orcid.org/0000-0001-5525-5447, Wedmore, LNJ et al. (6 more authors) (2021) Determining histories of slip on normal faults with bedrock scarps using cosmogenic nuclide exposure data. Tectonics, 40 (3). e2020TC006457. ISSN 0278-7407
Abstract
Cosmogenic exposure data can be used to calculate time-varying fault slip rates on normal faults with exposed bedrock scarps. The method relies on assumptions related to how the scarp is preserved, which should be consistent at multiple locations along the same fault. Previous work commonly relied on cosmogenic data from a single sample locality to determine the slip rate of a fault. Here we show that by applying strict sampling criteria and using geologically informed modeling parameters in a Bayesian-inference Markov chain Monte Carlo method, similar patterns of slip rate changes can be modeled at multiple sites on the same fault. Consequently, cosmogenic data can be used to resolve along-strike fault activity. We present cosmogenic 36Cl concentrations from seven sites on two faults in the Italian Apennines. The average slip rate varies between sites on the Campo Felice Fault (0.84 ± 0.23 to 1.61 ± 0.27 mm yr−1), and all sites experienced a period of higher than average slip rate between 0.5 and 2 ka and a period of lower than average slip rate before 3 ka. On the Roccapreturo fault, slip rate in the center of the fault is 0.55 ± 0.11 and 0.35 ± 0.05 mm yr−1 at the fault tip near a relay zone. The estimated time since the last earthquake is the same at each site along the same fault (631 ± 620 years at Campo Felice and 2,603 ± 1,355 years at Roccapreturo). These results highlight the potential for cosmogenic exposure data to reveal the detailed millennial history of earthquake slip on active normal faults.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | active tectonics; cosmogenic isotopes; fault slip rates; quaternary dating; quaternary geomorphology |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 20 Aug 2021 12:16 |
Last Modified: | 20 Aug 2021 12:16 |
Status: | Published |
Publisher: | American Geophysical Union (AGU) |
Identification Number: | 10.1029/2020tc006457 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:177264 |